Cam



Aug. 14, 194s.

` G. L.. BENNETT `:a1-A1. 2,382,849 y CAM Filed April 3, 1942 2sheets-sheet 1 Inventors:

Gardell L. Bennett,

Frech-'ick Dger;

The@v Attgme,

Aug. 14, 1945.

G. L. BENNETT ET AL CAM I 2 Sheets-Sheet 2 Filed April C5', 1942Inventors'. Garde" .l' Bennett,

F edrick D ern b5 fvg, Their` Attorng.

Patented Aug. 14, 1945 CAM Gardell L. Bennett and Fredrick ZDyer,Schenectady, N. Y., assignors'.toiGeneralfElectric Company, acorporation of New-York Application April .3, 1942,Serial`No. 437,538

(c1. m-.sesi

2 Claims.

Our invention relates tocam operating means, more particularly to camoperating means for electric switches, and has for its object simple,reliable and inexpensive shockproof cam operatingmeans.

.In the operation of electric switches, a single cam against which-afollower member is held by means of a spring has the disadvantage thatit is ynot shockproof because of the fact that the spring is theoperating means in one' direction. For shockproof construction, twoopposed cam faces, i. e., a cam slot, is required but such cams arecostly, especially Where a sequence of movements is required.

In carrying out our invention, we provide a plurality of cam sectionshaving cam grooves in laterally different positions, `which sections areinterchangeable and may be assembled in desired relations to give thedesired shape of cam slot.

For the movement of a switch member between closed and open circuitpositions, we provide four diiierent interchangeable cam sections, onefor each position of the switch and one to effect movement of the switchin each direction.

More particularly, we provide oneor more rotatably mounted operatingmembers, each consistingof a disk sector provided with an arcuate sloton one side, which slot has for its center the axis of rotation of thedisk. In this slot we assemble the interchangeable cam sections therebyto form a cam slot on one side of the disk sector of such shape as togive the desired vsequence of operations.

Thus by suitably assembling thecam sections, the circuit controllingmember can be operated from one position'to another at any desiredangular position of the disk sector and maintained in either its closedor open circuit positionthroughout a predetermined amount of angularmovement of the disk sector.

For a more complete understanding of our invention, reference should behad to the accompanying drawings-in which Fig. 1 is a side elevationview, partly in section, of an electric switch embodying our invention;Fig. 2 is a plan view, partly in section, of the device shown in Fig. 1;Fig. 3 is a partial sectional view along the line 3-3 of Fig. 2 lookingin the direction of thearrows;` Fig. 4 is a detail planview showing theposition ratchet means; Fig. 5 is a detail perspective viewof. anoperating camdisk; whileFig. 6 isl an exploded view in perspective ofthe stop means for the rotatable element.

Referring to the drawings, in carrying'` cutour invention in one formweprovide asquare 'shaft Shaft.

lllhaving itsjjournal ends mounted inbearings l mounted'inpairs andthesectors of each pair are Y directlyopposite eachother in acommon plane.

As shown inFi'g. 5, each sectoris provided with a square recess 2l Aatits center into which one side of theshaft HJ ts and with atransverse'fhole 22 which registers with a ,tapped hole 23 in the Thusthe'two disk sectors of a `pair are placedon opposite sidesoffthe shaftl 0 Vwith their holes "22v registering withithe hole "23 after whicheachis secured separately .to the shaft'by a screw (not shown) engagingthetappedhole 213.

The sectors l5 to `20, inclusive, are identical. in construction.'Cooperating .with them are identi,- cal switch structures only three ofwhich, 2'4, 25 and 1'2'6, are shown. Each switch structure comprises acontact arm'21 (Fig.` l)V having a stationary ,pivot'28 at itslowerendandcarrying'a bridging contact 29 atits upper end. These contact armsare'made of an electrically insulatingma- .terial, preferably a moldedcompound such as. phenolic eondensationproduct.

vEach contact farm isprovided with a follower member'shown as aroller'SUsecured to the contactarm on one side andhavingits aXisofrotation parallel withthe axisofthe pivot `28. This roller extends intoa cam slot 3l, Fig. i5, in the side or faceof the disk sector adjacentthe contact arm whereby, `when the handle is moved to turn'the shaftand'disk sector, the sides of the slot '3 l onopposite'sidesofthe'roller 30 cause the rollertomove radially withrespect to'the shaft in conformity'withthe shape of the slot wherebythe-contact-arrne j'is moved between its closed and'opencircuitpositions.

' shownin Fig. 2,` the contact arms'21, -28 and '23 are :situated onlthecam slot sides ofthe sector 20, f8 1and IIS, respectively, -with Vtheoperating roller-30 of reach eont-actiarm extending into the is providedwith a pin 38 on its inner side whichsiz. extends through a hole 39 inthe disk sector. On

its outer end this pin is provided with a peripheral groove (not shown)forming a small shankV over which is slipped a forked spring retainingmember or clip 40. This clip 4D when it is inserted in place iscompressed against the side of the disk sector l thereby to hold the camsections in place, and

the prongs of the clip 40 are separated somewhat' so that the clip issecured in place although it y maybe readily removed by a suitable tool,such as a screw driver.

Inkview of the fact that the switch arm 21 has only two positions, thatis, a circuit closed position and a circuit open position, we have foundthat by providing four different cam sections 33, a cam slot 3| can bebuilt up with the sections to give the desired movement of the contactarm at any desired angular position of the disk sector- `and maintainthe contact arm in any desired position. Thus, referring to Fig. 5, itwill be observed that four dierent sections are providedan open circuitpositional section 33a, a transfer section 33h which moves the switcharm from the open tothe closed circuit position, an open circuitpositional section 33o, and a transfer section 33d which moves thecontact arm from the closed back tothe open position.

These four cam sections 33a to 33d have the same overall size andconstruction so that they are interchangeable and have the same width ofcam slot. They differ, as shown in the drawings, in the position of theslot adjacent one side or the other of the groove 32, i. e., as shown,in a radial direction, the positional sections 33a and 33o having,`respectively, radially inner and outer slots, while the transfersections 33h and 33d have radially or'obliquely extended slots arrangedto'join the slots of the sections 33a and 33e for, respectively,radially outward orinward movement of the roller. Thus, the sections 33band 33d are the ones that produce radial movement of the roller.

`Considering the particular cam slot assembly shown in Fig. 5, beginningat the upperend, i. e., the counterclockwise extremity of the slot 3|,it will be observed that the roller is in its radially innermostposition and holds the switch arm in its open circuit position. As thedisk sector is turned in a counterclockwise direction, the contact armis moved by the third cam section to its closed circuit position whereit is maintained over two cam sections. Then the contact arm is movedback to its open circuit position where it is maintained for four camsections, after which it is moved to its closed circuit position,maintained there over one cam section, and then returned to its opencircuit position over the next three remaining cam sections.

Preferably, the sectors to 20inclusive, and the cam sections 33 are diecast so that they do not require machining.

As shown in Fig. 1, the contact arm 21 is mounted on a metal supportingbracket 4| and. this bracket in turn is secured by a screw 42 to a crosssupporting bar 43 secured to the bottom section I3 of the casing. Thebracket 4| has a portion 44 extending upward above the cross bar 43 andto this portion is secured by a screw 45 a support 46 for the stationarycontacts 41 and 48. This support 46 is also made of an electricallyinsulating material, preferably a molded material.

Thus, it will be observed that by removing the screw 42, the bracket 4|can be released from the cross bar 43 and each switch assembly removedas a unit. In order to secure the bracket 4| against turning about thescrew 42, lugs 49 are provided on the lower end of each bracket whichare in engagement with the cross bar when the screw is tightened.

In order to define the various angular positions of the shaft l0 for thedesired switching positions, a metal disk sector 50, Figs. 2 and 4, issecured to the shaft with a separate sector 5| on the opposite sides ofthe shaft for indicating the open position only. These sectors 50 and 5|are secured to opposite sides of the shaft bymeans of separate screws,as shown. A spring pressed roller bears on the periphery of each ofthese sectors 50 and5 only one roller 52 (Fig. 2) bearing on the sector5| being shown in the drawings. This roller is mounted on the upper endof an arm 53 (Fig. l) having a xed pivot 54 on the casing and biased ina counterclockwise direction, as seen/in Fig. 1, by a compression spring55. An adjustable nut 56 is provided for the xed end of the spring andby adjusting the position of this nut on its supporting bolt 51 theforce applied by the spring can be adjusted as'desired.

The two separate arm wheels 50 and 5| are provided in order that someparticular position, suchas the open position, for all of the contactarms can be designated to the operator as he moves the handle. vThus thesector 5| is provided with a single depression 58 for its roller 52, acorresponding depression 59 being provided on the othersegment for itsroller (not shown). When these two rollers are in these depressions, amuch greater force is required on the part of the operator to turn theshaft and sectors to the next position in either direction. Thisincreased holding force is an indication to him that the switch is inthis particular position.

Furthermore, with the separate positioning rollers, the spring pressureof each can be adjusted independently. Preferably, the adjustment issuch that a relatively light pressure is applied by the roller to thesector 50 whereas the roller applies a relatively great pressure to thesector 5|. `When the roller is out of the depression 58, however, itdoes not appreciably impede the rotation of the shaft because it bearson the remaining smooth arcuate surface ofthe sector 5|.

In the switch disclosed, six operating sectors and six contact arms areshown for a multiplicity of control steps, for example, in the startingand control of an electric motor. Obviously, any suitable number ofsectors and contact arms can be used'to suit the requirements. l

An adjustable limit stop means is also providedV for limiting the arcthrough which vthe sectors can be iturned. In View of the fact that eachsector is slightly less than in extent, the permissible rotationof theshaft IU must be limitedvto less 1than180" 'in any case. This iseffected by stop projections 60 and 6| (Fig. 2) on the casing onopposite sides of thesh'afty I0 at `thehandle end. On the shaft adjacentthe handle'are two stop segment members 62 and 63 having projections 64and 6,5 (Fig. 6) extending out far enough from the shaft to engage thestop 66 or 6I. These members are provided with holes 66 and 61 lthroughwhich a hub 61a on the handle extends loosely. Also, they are providedwith arcuate series of adjustment holes 68 and 69 through someregistering two of 'which the screw 16 extends and is seated in athreaded aperture 1| in the lower end of the handle.

It will be observed that for the greatest possible amount of movement ofthe shaft l0, .the two stop members 64 and 65 will be in registeringrelation. For a decreased amount of rotation, the members 62 and 63' areturned on the hub 61a with respect to each other so as to separate theprojections 64 and 65 as desired, after which the screw 10 is insertedand the members clamped to the lower end of the handle.

The lower supporting pant of the casing vI3 is provided with an upperremovable portion 12 carrying a gasket 13 to provide a sealed jointbetween the two.

While we have shown a particular embodiment of our invention, it will beunderstood, of course, that we do not wish to be limited thereto sincemany modications may be made, and we therefore contemplate by theappended claims to cover any such modications as fall within the truespirit and scope of our invention.

What we claim as new and desire to secure by Letters Patent of theUnited States is:

1. The combination with an operating shaft of means for turning saidshaft, a disc member secured to said shaft and rotatable with saidshaft, said disc member being provided with an arcuate groove on oneside near its periphery having for its center the axis of said shaft, aplurality of pairs of interlocking means on the walls of said groove,the interlocking means of each pair being oppositely disposed from eachother in a radial direction with respect to said disc member, aIplurality of interchangeable cam sections mounted in said groove, eachof said cam sections being provided with securing means at each endcooperating with one of a pair of said interlocking means whereby saidcam sections are secured against movement along said groove, said camsections having each substantially the same overall dimensions and beingin side-by-side relation when mounted in said groove, each of said camsections being provided with a cam slot having a predetermined radialwidth and said sections being arranged with said cam slots communicatingwith one another to form a continuous cam slot, there being sectionshaving arcuate slots respectively adjacent their radially outer andinner ends and a cam section between said last mentioned sections havinga connecting transfer cam slots extending obliquely with respect to theradius of said disc member passing through said transfer cam slot soas-to join together said arcuate cam slots, a movably mounted drivenmember, and a follower member on said driven member lying in saidcontinuous cam slot whereby upon rotation of said disc member saiddriven member is moved radially by the walls of said transfer cam slotbetween inner and outer positions, said follower member being locked bythe walls of said arcuate cam slots in each of its inner and outerpositions against movement radially in each direction.

2. The combination with an operating shaft of means for .turning saidshaft, a'disc member secured to said shaft and rotatable with saidshaft, said disc member being provided with an arcuate groove on oneside near its periphery having for its center the axis of said shaft, a'plurality of pairs of projections on the walls of said groove, theprojections of each pair being oppositely disposed from each other in aradial direction with respect to said disc member, a plurality ofinterchangeable cam sections mounted in said groove, each of said camsections being provided with a slot at each end whose walls embrace oneof a pair of said projections whereby said cam sections are securedagainst movement along said groove, means securing said cam sections insaid groove, said cam sections having each substantially the sameoverall dimensions and being in side-by-side relation when-mounted insaid groove, each of said cam sections being provided with a cam slotlhaving a predetermined radial width and said sections being arrangedwith said cam slots communicating with one another ;to form a continuouscam slot, there being sections having arcuate slots respectivelyadjacent their radially outer and inner ends to form outer and innerarcuate cam slots having for their center the axis of said shaft and acam section between said last mentioned sections having a connectingtransfer cam slot extending obliquely with respect to the radius of saiddisc member passing through said transfer cam slot so as to jointogether said outer and inner cam slots, a movably mounted drivenmember, and a roller on said driven member lying in said continuous camslot whereby upon rotation of said disc member said driven member ismoved radially by the walls of said transfer cam slot between inner andouter positions, said roller being locked by the walls of said arcuatecam slots in each of its inner and outer positions against "H" movementradially in each direction.-

GARDELL L. BENNETT. FREDRICK DYER.

